A test that measures electrical activity in muscles to assess nerve and muscle function.

Overview of the Condition

Carpal tunnel syndrome is a common condition caused by pressure on a nerve in the wrist. It can lead to numbness, tingling, pain or weakness in the thumb and fingers. It may be related to repeated hand movements, wrist structure or certain medical conditions. Treatment usually helps relieve symptoms and improve hand function.

Causes / Why It Happens

Carpal tunnel syndrome occurs when pressure is placed on the median nerve as it passes through a narrow space in the wrist called the carpal tunnel. This nerve helps provide feeling and movement to parts of the hand and fingers. Swelling, inflammation, wrist injuries, arthritis or repeated strain on the hand and wrist can irritate or compress the nerve. In many people, there may not be a single clear cause.

Signs and Symptoms

• Tingling in the thumb and fingers
• Numbness in the hand or fingers
• Shock-like sensation in the hand or wrist
• Pain or sensation spreading up the arm
• Symptoms worsening at night
• Symptoms while holding objects such as a phone or steering wheel
• Weakness in the hand
• Difficulty gripping objects
• Dropping objects more easily

Diagnostic tests

• Ultrasound: A scan that shows pictures of the wrist to check if the nerve is being squeezed
• EMG (Electromyography): A test that checks how well the muscles and nerves are working
• Nerve conduction study (NCS): A test that uses small electrical impulses to see how well signals travel through the nerve in the wrist

Test overview and preparation

Electromyography (EMG) is a test that checks how well the muscles and the nerves controlling them are working. It helps diagnose nerve and muscle disorders causing weakness, numbness or tingling.

Preparation Guidelines

• Bathe before the test and wear comfortable clothing
• Avoid applying creams or lotions on the skin
• Inform your healthcare provider about medicines, bleeding disorders or implanted devices such as a pacemaker

Step-by-step

• You will sit or lie down comfortably
• A thin needle electrode will be inserted into selected muscles
• You may be asked to relax or move the muscle gently
• The electrical activity of the muscles will be recorded

Time required

30 to 90 minutes

Risks and benefits

Risks

• Mild discomfort during needle insertion
• Temporary soreness or bruising at the test site
• Serious complications are rare

Benefits

• Helps identify nerve and muscle problems
• Assists in diagnosing conditions such as carpal tunnel syndrome and neuropathy
• Helps doctors plan appropriate treatment

Myths & Facts

Frequently Asked Questions